InuYasha first became aware of the sword when Sesshoumaru was seeking it; in the end InuYasha wound up with Tetsusaiga and Sesshoumaru was given Tenseiga, a healing sword-- to his dismay. Tetsusaiga was protected by a barrier that prevented non-humans who wish to harm humans from getting near it, preventing Sesshoumaru from touching it. InuYasha, with the help of his human companion Kagome, were able to grab it.

The sword allows its owner to make use of two attacks while in its transformed state which are:

Kaze no Kizu (Wind Scar)- A powerful blast of sweeping energy that is said to be capable of slaughtering 100 demons at once.

Bakuryuha (Backlash Wave)- The ougi (ultimate technique) of the Tetsusaiga which allows the sword's owner to use the enemy's aura of power against them in a devastating counterattack. However, this technique will only take effect against enemies that make use of youki (demonic power).

The sword also has the ability to take in the power of full-blooded youkai (demons) to create new attacks for Tetsusaiga.